I have found an NCR 6500/1 40 pin CPU (MCU?) on the PCB of an old Seagate HDD. The PCB is marked Control ST-225 Assy 20301 Rev 003. My example has the date of manufacture code 8640S which translates to the 40th week of 1986 (most of the 74 series TTL chips on the board also have similar date codes, a few examples: 8638, 8629, 8632, 8637 & 8627 so we know it was still being manufactured in 1986).
6500 family
Usage of NCR 6500/1
I have found an NCR 6500/1 40 pin CPU (MCU?) on the PCB of an old Seagate HDD. The PCB is marked Control ST-225 Assy 20301 Rev 003. My example has the date of manufacture code 8640S which translates to the 40th week of 1986 (most of the 74 series TTL chips on the board also have similar date codes, a few examples: 8638, 8629, 8632, 8637 & 8627 so we know it was still being manufactured in 1986).